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mattr writes "Japan's Obayashi Corp. has announced plans to build a space elevator by 2050. They are famous for wrecking skylines with the over-sized bullet train station in Kyoto, the world's tallest self-supporting tower Tokyo Sky Tree and just recently, the beginnings of the Taipei Dome. It will take a week at 200 kph for your party of 30 to reach the 36,000-km-high terminal station, while the counterweight [swings along at] 96 km high, a quarter of the way to the Moon."

1. The fact that we don't have the necessary structural materials yet to actually make a space elevator.

2. Neither Japan nor any Japanese company has the financial solvency to undertake such an effort

2. No no wants to spend a week in an elevator even if it means you get to go into orbit. Christ I can barely make it to the 15th floor without some jackass farting. A whole week. Don't think so.

Every so often some company in need of cashflow creates some nonsensical grandiose concept in the hopes of securing ignorant investor funding (See Moller flying cars). And such companies usually have spent the bulk of the cash on P.R. - hence the slashdot article.

The fact that we don't have the necessary structural materials yet to actually make a space elevator.

And we'll continue not having them until someone pays to build a space elevator and does the needed research. By 2050 it's not impossible to think materials will be around to make this feasible.

Neither Japan nor any Japanese company has the financial solvency to undertake such an effort

Possibly, hard to say. They put up some really large buildings. They could get a huge loan.

No one wants to spend a week in an elevator even if it means you get to go into orbit.

I would happily pay 20k to go to said stationary station for a few days. Even if it took a week to get there in cramped quarters.

By then there may be a number of cheaper options to visit pace though, Virgin Galactic is making a go at it. I really only want to go up if I can spend a day or two though, so mere flights up and down do not interest me much...

You are correct. However some dream that the market will provide in some mysterious way without paying materials scientists to find something that will make it technically possible and some engineers that can turn that it a workable design. Then we need an offplanet project big enough so that the huge project of making a beanstalk is worth it.These stories bring out a lot of clowns that think you can just throw stuff in the air and it won't come down, and reader, if you don't want to be seen as one of those clowns I suggest you look at the wikipedia page on these beanstalks then read and understand the very simple maths and physics before posting. A rotating frame of reference is a bit hard to get used to initially, so get your head around it before posting stuff that anybody with an engineering or physics background here will scoff at as magical thinking.

By then there may be a number of cheaper options to visit space though, Virgin Galactic is making a go at it.

I dont believe they will ever be cheaper. Also, they're not even reaching low earth orbit yet (at the moment they're scraping 110km or something).

Space elevators on the other hand will go up to geostationary at least (as the summary says: 36000km), and they're far more efficient, I suspect (rocket motor spewing stuff all over the place versus electrical lift running up a tether).

Usually step 2 is get investors believe you and give you lots of money. Note that to profit, you don't need to actually manage to build the space elevator. You just must make sure that it doesn't look like fraud.

If it were that easy to build a space elevator, then we would be talking about making one in 2020, not 2050. The point of the exercise is to clarify exactly which engineering hurdles must be overcome. Nanotubes are very new technology. We still have ~30 years in which to mass produce it.

"Elevator" is indeed a slight misnomer in that the there is no external mechanism to pull the car up. The car propels itself on the cable, which makes it more like an electric train that propels itself on a pair of rails. That said, this is hardly a dumbing down of the technology--the word "elevator" accurately conveys the fact that the car is electrically operated on a motor along a piece of cable. What is your beef?

Please do propose an alternative method to elevate the payload once you get outside of atmosphere that is less "horribly inefficient" than space elevator. The only other proven method known to humanity is chemical rocket, which is orders of magnitude less efficient than electric rail because the rocket requires you to carry the propellant with you, whereas with the rail system the rail delivers the electricity to you.

No no wants to spend a week in an elevator even if it means you get to go into orbit. Christ I can barely make it to the 15th floor without some jackass farting. A whole week. Don't think so.

To get from Vladivostok to Moscow on the train you would need 9 days. It used to take a couple of weeks or more. One train carriage carry approximately 30 people and the either share cabins with 3 other travellers or the whole carriage is one big cabin. People used to travel this way all the time before flying started to be an option.
I suppose with our iPads etc the journey will be even less difficult

And we'll continue not having them until someone pays to build a space elevator and does the needed research. By 2050 it's not impossible to think materials will be around to make this feasible.

Not true. The utility of a 63GPa material with the density in the 3000-2000kg/m3 department is so ridiculously awesome that its is indistinguishable from magic compared to today's materials. Think *easy* to build SSTO RV rockets for starters. Even if expensive its just plain awesome. You don't need space elevators for motivation.

However it is not a given such a material is even possible. Bulk material strength is always far less that perfect theoretical strength. There has already been a paper suggesting that SWCN may not be up to the task due to "dislocations".

Also it may not be economical even if you have the material. The same material makes alternatives much cheaper too, such as plain old boring rockets. Or more exotic ideas such as launch loops or tethers.

Finally there is the problem with transit time. If you spend too long in the radiation belts, this is probably the last thing you would do..... A week sounds too slow.

We do not in fact have the materials. No matter how much money you spend you cannot get even a foot of +6GPa strength cable. Not only have we not ever made such a material, but we don't know how yet either. It is a R&D project. It is also not a given that it is even possible.

Fair enough. Basically, the cable is always going to be stressed to a large percentage of maximum loading. It will also be made of carbon, which is flammable. I suspect that many kinds of weaponry could cause just enough damage to cause it to unravel and fail in short order. An incendiary charge placed against the side of the cable with a swarm of R/C helicopters might work just as well.

In any case, it's the ultimate in single point failure. Yes, you can attempt to secure the cable with missile defenses and other weaponry, as well as elaborate security checks of everyone allowed near it. I just can't see such an effort working when it's so trivial to actually destroy the cable, however.

Without substantial advancements in material research, this cannot happen. No current or upcoming material exists that can withstand the extreme shear forces that would be exerted on a space elevator.

Space elevators are currently the realm of science fiction, and will likely remain so even in 2050. If we had the technology and materials to build it right now, a 2050 completion would still be unlikely. And we have neither the tech nor the materials.

Even if they don't do it, I'm pretty sure in the process they're gonna find/invent some cool stuff that will probably make them a shitload of money. They are doing exactly what all technology companies should be doing: push the limits and try the impossible. It's always a win-win idea.

Space elevator : Initial cost is very very high but once built the running costs are negligible

Rockets : Initial cost is high but not that high, running costs are high forever, economy of scale will never kick in to any reasonable degree

Once you have built a space elevator, all rocketry for lifting will be obsolete - most of a rocket is there to lift the rocket into orbit not the payload... a space elevator will be externally powered so will not need to be any heavier than needed to climb the cable..and you might be able to drive it and fund it with materials coming down (mining the asteroids)

The concept of a space elevator is so out there but I expect if one did come into existence that people would be carried up in something more resembling a submarine than a box. It'd have to be pressurized, radiation shielding, temperature control, powered in some way to climb, have sleeping area, food preparation area, sanitation etc. All designed to work in gravity and zero gravity.

If people can live on a sub for months at a time they'd be able to live on an elevator for a week. I assume these people wouldn't be randomly plucked off the street and would undergo some form of training resembling existing astronaut programs.

Based on many of the comments here, I think many people consider this elevator to be like existing internal building elevators - capable of housing a dozen people standing as they are raised. Think more of a vertical train, with seats/beds that could recline 400-500 people while they are propelled out of the atmosphere. By the textbook definition of 'elevator', I guess it a reasonable term, but I think it understates the possibilities by an order of magnitude.

Once outside the atmosphere, the greatest enemy (air resistance) is gone. Speeds of 200kph are painfully slow, and based on rail technology.

You have asked for an alternative elevation technique, so let me offer some suggestions - without giving any thought to their feasibility.

What about a railgun? What about a swinging rope (like a chimpanzee swinging from branch to branch)? What about a tethered coil orbiting the central cable, rather than travelling along it? Why not pump high pressure atmosphere from the surface, and use it as a propellant?

Some of these technologies will be problematic for humans as we are not very resistant to high G-forces, but they would be ideal to exploit the opportunity to accelerate masses into space.

They are doing exactly what all technology companies should be doing: push the limits and try the impossible. It's always a win-win idea.

History is littered with the remains of companies who tried to push the limits, attempt the impossible, and failed. True, pushing limits can be extremely rewarding and is the foundation of technical progress, but it's by no means the panacea you imply!

Aerospace engineer who has worked on orbital tether design speaking here.

A cable with a tip velocity of 30% of orbital speed is feasible with existing materials. Since the center of the cable is at orbital velocity by definition, the tip is then at 70% of orbital velocity at the bottom of it's rotation. A vehicle coming from the ground then needs half the kinetic energy as a full ground-to-orbit one does (Kinetic energy goes as 0.5 times velocity squared). That makes single stage launch vehicles very feasible. If the tip is at 1 gravity, then the cable radius is 516 km, and the center would be at an altitude of 750 km or thereabouts, so it does not see too much drag at the low point. Half a rotation later (12 minutes) at top of the rotation, you can let go, and now be going at 130% of orbit velocity, which is nearly GEO transfer or escape. Escape is 141% of orbit velocity.

If you wanted to get to zero g, then it's a 516 km ride, which beats the fuck out of a stationary elevator. The elevator will be heavy relative to the vehicles coming up and down, but you need onboard propulsion to make up for traffic differences. Anything going up tends to lower the elevator orbit, anything going down tends to raise it. Whatever is left over you need to make up, preferably with an efficient electric thruster. Arrival means landing on a platform that is at one gee. With modern GPS and laser navigation, that should be fairly easy. Make the platform hundreds of meters wide if you need a bigger target. Missed landings just means the vehicle heads back down sooner than it was supposed to. It should not present a safety problem.

Building something like this is a bootstrapping task. Start with a small rotating station, and extend cables from it. Keep adding sections of cable one at a time. Get your cable from near earth asteroids which have carbon, so you don't have to launch the whole thing from Earth. As the thing grows, the velocity to reach it from the ground goes down, so the payload a vehicle can carry goes up.